The studies proposed are for the treatment of acute leukemia and many of the solid tumors of children. The new patient study for acute lymphocytic leukemia will divide patients into 3 prognostic groups based on initial WBC and age. Treatment for each group will be trailored to that group. New tumor studies include the use of adjuvant chemotherapy with cytoxan and vincristine for children with Group V retinoblastoma and the use of cytoxan, vincristine and adriamycin for extraocular retinoblastoma. Ovarian tumors will be treated by primary surgery, radiotherapy if tumor is present after 2 courses of chemotherapy, and a 9 week course of chemotherapy using cis platinum, velban, and bleomycin on days 1 to 5, cytoxan and actinomycin D on days 21-25, and adriamycin on days 42 and 43. An amended histiocytosis X study will evaluate in greater detail the immunologic status of children under 2 years of age. Controlled brain tumor studies are evaluating the adjunctive use of CCNU, vincristine and prednisone with radiotherapy in medulloblastoma, ependymoma, Grade III and IV astrocytoma, and brain stem gliomas.